By way of introduction, phone phishing or fraud calls are in a growing trend recently. The danger of these fraud calls goes beyond the danger to regular users when these calls are placed to the Internet of Things (IoT) connected-car systems where they may distract drivers by taking the driver's attention away from driving. Fraud calls may also be problematic in other domains.
Traditionally, blocking calls from unwanted callers may be achieved by validating the caller ID within the telephone network before calls reach the receivers. This method checks the caller ID information and blocks calls except those from the caller ID on an allowed caller-ID list. This service is called a whitelist or caller ID filtering service, and it is widely deployed.